Protopine

Protopine is derived in the plants such as the opium poppy, Papaver somniferum, from the benzylisoquinoline alkaloid (S)-reticuline through a progressive series of five enzymatic transformations: 1) berberine bridge enzyme to (S)-scoulerine; 2) (S)-cheilanthifoline synthase/CYP719A25 to (S)-cheilanthifoline; 3)  (S)-stylopine synthase/CYP719A20 to (S)-stylopine; 4) (S)-tetrahydroprotoberberine N-methyltransferase to (S)-cis-N-methylstylopine. The final step is oxidation by the enzyme methyltetrahydroprotoberberine 14-monooxygenase: ==Metabolism==

The enzyme protopine 6-monooxygenase converts protopine into dihydrosanguinarine. NADP+ and water are the by-products. The enzyme uses reduced nicotinamide adenine dinucleotide phosphate (NADPH), and oxygen, with the initial product being 6-hydroxyprotopine, which spontaneously forms dihydrosanguinarine, found in plants such as Sanguinaria canadensis. == See also ==